Electrothermally operated valve



June 1936- J. v. GIESLER ET AL 2,044,427

ELECTROTHERMALLY OPERATED VALVE 'Filed Aug. 3, 1932 3 Sheets-Sheet 1aw-MW a w ws June 1936- J. v. GIESLER ET AL ELECTROTHERMALLY OPERATEDVALVE Filed Aug. 3, 1952 3 Sheets-Sheet 2 gvwe/whoaa Sum/M4 35 June 16,1936. J v, GIESLER ET AL 2,044,427

ELECTROTHERMALLY OPERATED VALVE Filed Aug. 3, 1932 3 Sheets-Sheet 3Patented June 16, 1936 UNITED STATES ELEGTROTHERMALLY OPERATED VALVEJean v. Giesler and William B. Mackintosh,

Knoxville, Tenn., assignors to The Fulton Sylphon ,Company, Knoxville,Tenn, a corporation Delaware Appli tion August 3, 1932, Serial No.627,358

21 Claims. (Cl. 23648) This invention relates to electrically-controlledpressure-operated devices, and particularly to devices of that characterfor controlling the flow i of a heating medium, such as steam, as forexample in house heating radiators. Therefore the invention will beexemplified as embodied in an electrically-controlled valve, preferablya modulating valve, applied to any suitable radiator, although in someof its broader aspects the invention is capable of wider application.

It has heretofore been proposed to operate valves, dampers and the likeby an electrothermallyroperated motor element wherein a heating chamberhas associated therewith an electric heating coil that is energized asthe result of changes of condition in the medium which constitutes thesource of control. Thus it has been proposed to provide anelectrothermally-operated motor including an expansible and collapsiblechamber and an electric heating coil, said chamber being charged with asuitable volatile fluid whereby the heating coil may volatilize saidfluid and, by increase of vapor pressure in said expansible andcollapsible chamber, cause expansion of said I chamber to actuate themeans to be controlled.

In such a construction all of the energy required to move the means tobe controlled must be derived from the electrical energy. This not onlyinvolves the consumption of considerable quantities of electricalenergy, but it necessarily involves a considerable time lag in order toderive from the electrical energy a sufllcient increase of thermodynamicenergy from volatilization of said liquid and increase of vapor pressureto effect the volumetric as well as the pressure changes required toexpand said chamber and operate said means to be controlled.

It is an object of this invention to provide a device of the characterreferred to which has a minimum of time lag and which is also economicalin its use of electric current.

Another object of this invention isto provide a valve having anelectrothennally-operated motor element for controlling the flow of aheating medium wherein a substantial part .of the energy required tooperate said valve is derived from the heated medium, thereby effectinga material saving in the amount of electric current consumed andimposing on the heating coil little more than the function of a relay todetermine the pressure that shall exist in the motor.

Another object of this invention is to provide anelectrothermally-operated motorhaving a heating chamber and anexpansible and collapsible chamber in communication therewith and-operatively connected to the means to be controlled, wherein theheating chamber contains but a relatively small volume ofvolatile liquidso that the delay incident to the development of the required vaporpressure will be reduced to a minimum, thereby both increasing thesensitivity and decreasing the time lag of the electrothermany-operatedmotor.

Another object of this invention is to provide anelectrothermally-operated motor for operating 10 a radiator valve or thelike wherein much of the energy required for effecting the operation ofthe motor is derived from the heated medium to be controlled and whereinthe sensitivity of the device is increased, and the time lag decreased,by 15 subjecting only a relatively small volume of the thermosensitivefluid to the heating effect of an electric coil.

Another object of this invention is to provide anelectrothermally-operated valve or the like :0 which is highly sensitiveand quickly responsive to temperature fluctuations;. and also one whichis relatively economical in its use of electric current.

Another object of this invention is to provide 25 anelectrothermally-operated valve or the like which is capable ofaccurately and economically maintaining a substantially uniformtemperature because of its avoidance of the considerable temperaturefluctuations which have been incident 30 to the use of devices of thischaracter as heretofore proposed.

Another object of this invention is to provide anelectrothermally-operated valve or the like wherein the electric heatingelement is sensitively 3 and accurately responsive to fluctuations intemperature in the controlling medium. Various forms of variableresistances have heretofore been proposed for controlling the flow ofelectric current through a heating coil. Carbon pile rheostats have beenfound to be somewhat erratic in operationas the resistance value for agiven setting tends to change with the lapse of time, while bonsiderablepower is required for their effective operation. Rheostats andpotentiometers using slidable contacts are also open to more or lessserious objections, inasmuch asthey not only tend to wear with continueduse but the friction between the relatively movable contact elementstends to introduce an objectionable time lag, particularly if there issufllcient pressure between the contacting elements to assure a positivecontact. Not only must considerable force be exerted upon the movablecontact to overcome the starting friction, but this friction tends tovary 'point is not higher, but preferably somewhat ible vessel.

with lapse of time, because of the accumulation of dust, oxides or otherforeign substances on the contact surfaces. If the sensitivity andresponsiveness of the electrothermally-operated motor "are to be fullytaken advantage of, the control circuit should be at least equallysensitive and responsive, and therefore it is the object of thisinvention to take full advantage of the sensitiveness and responsivenessof the electrothermallyrately responsive to progressive changes in thetemperature of the controlling medium.

Another object of this invention is to provide anelectrothermally-controlled motor with a heating coil which may operateintermittently or in a step by step manner but wherein the control ofthe heating 'coil is sensitive and accurate in its response to thepredetermined conditions of its actuation. I I

Another object ofthis invention is to provide a modulating radiatorvalvewith an electrothermany-controlled motor wherein the heating coilis progressively energized by means promptly, accurately and sensitiveb'responsive to changes of temperature, tofthe end that a substantiallyuniform temperature may be maintained.

.Another object of this invention is to provide a device of the typejust characterized which is relatively simple in construction and ruggedin use, as well as economical in operation.

Other objects of the invention will appear as the description of theinvention proceeds.

Stated broadly the electrothermally-operated control of the presentinvention includes an expansible and collapsible vessel which issubiected to a heated-medium, such as steam or any other suitable heatedmedium; Communicating with said expansible and collapsible vessel is aheating chamber of relatively small volume and containing a volatileliquid the vapor of which normally iills the expansible and collaps-Said heating chamber is subjected to the control of an electric heatingelement. Said volatile liquid is so selected that its boiling lower,than the normal temperature of said heated medium. Therefore, theexpansible and collapsible vessel, because it is subjected to thetemperature of said heated medium, is filled only with the vapor of saidvolatile liquid. As the amount of liquid in the heating chamber isrelatively small, there is no large volume of liquid that must first beheated by the heating coil in order to raise the vapor pressure, andtherefore ,pressure is substantially uniform throughout this opensystem, and any increase in pressure in the heating chamber under theaction of the heating coil is therefore accompanied by an increase inpressure in the vapor in the expansible and collapsible chamber. Anyincrease of pres sure in the heating chamber is also accompanied by sometransfer of the volatile fluid from the 5 heating chamber to theexpansible and collapsible vessel, and this is particularly the casewhen said vessel expands and therefore increases its volume in order toactuatethe mechanism connected thereto. But whereas the heating coil isthe source of energy for effecting the increase in pressure in theheating chamber and the transfer of a portion of said fluid to theexpansible and collapsible vessel, the heated medium surrounding thelatter is the source of a large part ofthe heat and energy by which workis done by the expansion of said vessel. Hence the .heated medium, whichis .more difllcult to control, may be controlled by means which derivesa substantial part of its energy from this heated 20 medium but whichmeans may be sensitively controlled with a minimum of time lag from amoreeasily controlled electric circuit while using the' electric currenteconomically.

While the invention as so,far characterized 25 may be used with meansfor making and breaking or intermittently actuating the circuit throughthe heating coil, or with means heretofore known for varying the currentthrough a heating coil, the present invention in its preferredembodiment, and to take full advantage of the sensitiveness andresponsiveness of the electrothermally-operated motor heretoforecharacterized, also includes means which normally maintains a slightthough continuous flow of electric current through the heating coil andwhich is sensitively and accurately responsive to small fluctuations oftemperature by using a variable resistance in circuit with said coilwhich avoids fluctuating characteristics, impositive connections, timelags, variations in frictional opposition to relative movement, etc.

The invention is capable of receiving a variety of expressions, some ofwhich are shown on the accompanying drawings, while certain featuresthereof can be used without other features thereof; therefore thedrawingsare to be considered as for purposes of illustration only, andnot as a definition of the limits of the invention, reference-being hadto the appended claims for that purpose.

Referring to the drawings, wherein like reference characters indicatecorresponding parts in the several figures,

Fig. 1 shows an elevation, partly in section, of a modulated radiatorvalve embodying the present invention;

Pig. '2 is a horizontal cross section through the top chamber of thevalve unit;

Fig. 3 is an axial section through a thermo- 60 statically controlledvarying resistance;

Fig. 4 is a front view of the thermostatically controlled varyingresistance of Fig. 3;

Fig. 5 is a somewhat schematic view to illus- 65 trate the principle ofthe electrothermally-operated motor of the present invention;

Fig. 6 illimtrates the use of a make and break electric control for theheating coil in the embodiment of Fig. 1; and

Figs. 7, 8 and 9 are axial sections of variable resistances embodyingthe present invention.

First referring to Fig. 5, the electrothermallyoperated motor iscomposed of a relatively small heating chamber ill, of any suitableform. conlar wall or bellows i5 brazed or otherwise suitably secured atone end vto' the base plate II and wall 20 suitably secured at i'ts openend to theperiphery of the base plate H. The interior of said chamber I9is supplied with a heated medium through pipe 2i, and egress forsaidheated medium or its condensate is provided by the pipe 22. Thewalls i3 and 20 are shown as spaced and connected by a thimble 23 whichhas, an aperture extending therethrough and which may form a part of thecommunicating piping between the chambers ill and I2. End wall i1 isshown as connected to a post or rod 24, which maybe connected to anysuitable means to be controlled, and a coil spring 25 is interposedbetween the movable end wall i1 and the base plate I to predetermine thepresure which must exist in the chamber i2 before the end wall il maystart to move to operate the rod or post 24.

The chamber III is charged with a volatile fluid whose boiling point isnot higher than, but is preferably somewhat lower than, the temperaturenormally maintained in the chamber is by the heatedmedium flowingthereinto or therethrough. Therefore, all of the volatile fluid existingin the vessel I2, is in the form of a vapor, and this vapor completelyfills said chamber in its normally contracted condition and held by thespring 25. The charge of volatile fluid, however,

and expansible and collapsible vessel l2, but they heating chamber l0being cooler than the expansible and collapsible vessel l2, the volatilefluid in said chamber, and also inthe major part of the piping Ii, is inliquid form.

Assume now that the temperature of the coil ill is increased. The heatdelivered thereby will result in an increase of pressure in the chamberIll, with a concomitant change of pressure throughout the open system,and there will also be some volumetric expansion of the liquid in thechamber Ill with the consequent flow of fluid therefrom into the vessell2. But the heat for volatilizing this transferred liquid is derivedfrom the chamber l9. When the pressure within the system reaches amagnitude sufficient to overcome the tension of the spring 25, vessel I!may begin to expand, with a further transfer of fluid from the chamberill, but again a large part of the heat required to perform the workincithe heating coil.

dent to volumetric expansion 'of the vessel It is derived from the fluidin the chamber ll. Hence the coil l8 furnishes the heat necessary fordetermining the, pressure that shall exist in the system and foreffecting the transfer of small amounts of liquid to the vessel 12 forperforming the requisite work. As the vol me of liquid in the chamberIII is relatively small, and canin fact be made but a small fraction ofthe volume of liquid that has heretofore been used in electro- 10thermally-operated motor elements, the liquid in said chamber ill willquickly reach the. temperature determined by the current flow throughthe heating coil l8, and as the energy for doing the work in the vesseli2 is largely derived from 15 the chamber Hi, there is little delay inthe response while the current is used economically in Hence theelectrothermally-. operated motor of the present invention quickly andsensitively responds with an economical consumption of electric energyto effect the desired actuation of the rod 25. 1

It is to be expressly understood that the relative volumes of thechambers Ill and i2 shown in Fig. 5 are not essential, as this flgurehas been drawn for purposes of illustration rather than for purposes ofshowing dimensions and volumes. The chamber l0 may be, and preferablyis, made as small as possible within the limitations imposed by theprinciple of operation just described. 30 The volume of the heatingchamber i0 must be sufiicient so that when the expansible andcollapsible vessel I2 is expanded to its limit, the vapor derived fromthe volatile liquidin said chamber will completely fill the system ofchamber ill 35 and vessel l2 under the existing pressure. The work donein the chamber ii) is therefore that required to move the liquid to thevessel i2 under the existing pressures, and is therefore proportional tothe pressure change and the change of volume of the liquid in thechamber Ill. The work done in the vessel I2 is also proportional to thepressure and volume changes, but the pressure change in the two chambersis substantially the same while there is a very substantial increase involume in the vessel i2. In other words, for each unit volume of liquidforced out of the chamber I 0 a much larger volume of vapor is formed inthe vessel I2, and thus the ratio of work done in the vessel l2 may bemany times that done in the chamber Ill, depending upon the ratio of thevolume of a given mass of the charging fluid when in the form of vaporat an average pressure to the volume of an equal mass of said fluid whenin liquid form. Additionally, the use of the heated fluid in the chamberis for effecting a substantial part-of the work to be done not onlymeans a saving in the electric current used in the heating coil but byreason of the use of less current, a more compact and sensitive controlfor the heating coil may be provided that will assure both sensitivityand long life.

Referring now to Figs. 1 and 2, a construction is illustrated embodyingthe principles above explained. Any suitable valve casing,30, providedwith inlet and outlet connections 3| and 32, has therein a suitablevalve seat 33 with which is designed to cooperate a valve disk 34 of anysuitable construction. Mounted on the top of the casing 30 and securedthereto in any suitable way, as by the ring nut 35 engaging the flange36, is a housing 31 for the heating chamber and heating coil. As shownsaid housing is composed of a cup-shaped wall suitably secured as byscrews 38 to an apertured base plate 39 whi rmed with or suitablysecured to the flange member 38. Mounted within the housing 31 is aheating chamber 40 shown as surrounded by and suitably in-' tricalconnections the heating chamber is made j as a tube and mounted inposition, adjacent each end thereof, by spring clips 44 carried byinsulating or insulated posts 45 secured to the plate 39. Theelectrical'leads 42 and 43 extend to suitable binding posts 48 on saidclips, as shown in Fig. 2, and therefore the electrical connections arecompleted, as well as the heating chamber mounted in position, by merelyforcing the same into retainin g engagement with said clips.

Adjacent one end the heating chamber 40 is provided with a filling tube50 which may be sealed in any suitable way after the charge has beenintroduced into said chamber, and leading from the opposite end of saidheating chamber is a pipe. 5|, which may be rigid or flexible and of anysuitable length and size, and which extends down to and is secured inthe end of a coupling nut 52. Nut 52 is threadedly attached at 53 to a.post 54 suitably secured to and projecting upwardly from the valvemember or its associatedparts and also having a recess 55 whichconstitutes a continuation of the conduit 5|, said recess having lateralapertures 56 communicat ing with the interior of the expansible andcollapsible vessel next to be described.

The expansible and collapsible vessel is formed by a relatively thindeeply corrugated tubular wall or bellows 51 suitably secured at oneend, as by brazing, to a flange 58 whereby it may be clamped influid-tight engagement with the wall of the valve housing 30, as by thering nut 35. The opposite end of the bellows 51 is suitably secured, asby brazing, to the valve disk 34 or, as shown, to a threaded collar 59suitably secured thereto. Collar 59 is threaded at its periphery and hasmounted thereon by means of said threads a tubular stop 60 which, byengagement with a flange or shoulder 6| formed on or suitably secured tothe post 54, determines the extent to which. the bellows 51 may becollapsed in providing a wide open position for the valve disk 34.Mounted on the post 54 is also-a spring abutment 62 and disposed betweensaid abutment and the closed end wall 53 of the tubular stop 50 is acoil spring 64 which predetermines the pressure which must exist in theexpansible and collapsible vessel before the latter may expand an movethe valve disk 34 toward closed position. The end wall of, the tubularstop 80 closely surrounds the post 54 and slides thereon to guide andmaintain rectilinear the expansible and collapsible movements of thebellows 51 and therefore the movements of the valve disk 34.

The expansible and collapsible vessel thus de ber 65 which is normallyfilled with the steam flowing through the valve casing 30. The volatilefluid charge in the electrothermally-operated motor in this case shouldhave a boiling point slightly below the normal temperature of the steam,and for example may be methyl alcohol or acetone, and the volume ofvolatile fluid introduced into the open system composed of the heatingchamber 40, pipe 5i and expansible and collapsible vessel 51 ispreferably such as to fill the heating chamber 40 and pipe 5|, while theexpansible and collapsible vessel 51 is filled with the vapor of saidfluid, when said vessel is in its most contracted position and the valve84 is most remote from its seat under the action of the spring 64. Thespring 64 is of such strength that the vapor pressure existing in thechamber 51 is insufficient to overcome its tension prior to apredetermirlied application of heat to the heating coil Heating coil 4|may be energized in any suitable way, but,v in accordance with thepreferred use of the present invention the control of said heatlngc ilis such as to take full advantage of the sensitiveness andresponsiveness of the electrothermally-bper'ated motor element asheretofore described. The'r'efore the regulation of the current flowingthrough the coil 4| is preferably effected by means which is not subjectto variations of operation and resistance to adjustment such as arecharacteristic of the use of carbon pile "rheostats and sliding contactrheostats, al-

/ though as will be apparent from the foregoing some of the advantagesof the present in- .vention would be obtained by controlling theelectrically insulating material such as glass, and .preferabiy ofarcuate form, and containing a bobbin II of suitable electricallyinsulating material such as porcelain, which may be grooved if desiredto receive the resistance element. Coiled aroundsaid bobbin H is a wireI! of suitable resisiance material, such as nichrome, said wire havingleads l3 and I4 projecting from the casing. Suitably mounted on oraflixed to the interior wall of the casing III is a second conductor orwire 15, which may also be of the same resistance material, having alead 16 projecting from the easing. Mounted within the casing is aglobule of mercury ll of sufllcient size so that it will bridge thespace between the wires 12 and 15 and form a good electric contact withboth. Casing 10 and its bobbin II have a common curvature, and thecasing 10 may be filled with a neutral or inactive gas, such asnitrogen. The casing II is designed to be mounted for oscillation abouta center which may be coincident with its center of curvature, and asthe casing 10 is tilted in one direction or the other of globule ofmercury TI will move by gravity along the wire I5 and include more orless of the wire 12 in the circuit, depending upon' the direction inwhich the tube II is tilted and which of the leads 13 or 14 is connectedin circuit with the lead l5the two leads I! and 14 being provided sothat the device can be connected to increase the resistance in thecircuit by tilting the tube in either one or the other direction,depending upon the exigencies of the installation. On

the other hand, by suitably connecting both of the fined by the bellows54 is disposed within a cham- I leads l3 and I4 into the circuit, thestructure of it assures that the resistance to operation and action ofthe device shall be uniform from one extremity to the other oi!itsran'ge of movement.

In place of providing a wire 15 along the wall of the variableresistance device as shown in Fig. -'7, the bobbin 1| may be wrappedwith two parallel resistance conductors l0 and 8|, the former havingleads 8! and I3 projecting to the exterior of the casing, and the latterhaving leads 84 and 85 projecting to the exterior of the casing. In thisconstruction the parallel wires are spaced sufficiently far apart toassure-that there will be no short circuiting, while the globule ofmercury 11 should be of sufllcient size to assure that it willalways'brldge the space.

between any two wires of said parallel windings. Otherwise, theconstruction and operation of. this device are the same as that shown inFig. I.

With the foregoing explanation of the principle underlying the variableresistance which it is preferred to use in the present invention, ref-,erence may be had to Figs. 1, 3 and 4 as showing the completeinstallation. Mounted upon any suitable base plate 99- is a thermostatof any suitable construction, here shown as a. bimetallic coil 9|suitably attached at one end to said base plate 90 at 92 and carrying atits .opposite end a clamp'93 in which is received the casing 10 of avariable resistance device such as shown in Fig. 8. Lead 82 from saidvariable resistance device is connected to the lead 43 in the heatingcoil 4i, while lead 84 from said variable resistance device is connectedto lead 42.0! said heating coil 4i through the low voltage secondary ofan induction coil 94, the primary of which may be connected into anyordinary house lightingcircuit.

The foregoing construction of variable resistance is designedto maintaina continuous current through the heating coil 4| when the device is inoperation. Sometimes, however, it is desirable that the heating coil beenergized only after predetermined increments of change have takenplace. When this is desired a variable resistance of the form shown inFig. 9 may be employed. In the form here shown the structure is similarto thatabove described in conjunction with Fig.

-'1 except that the bobbin 98 is provided at predetermined intervalswith projections 99 and the resistance wire 12 is passed over each ofsaid projections 99, and may or may not be wound around intermediatesections of the bobbin. The,

globule of mercury. 11 is of sumcient size to bridge the wire 12 at twocontiguous projections 99, but is not of sufflcient size to bridge threecontiguous projections 99. Hence the circuit through the heating coil isclosed when said globule 11 is bridging the wire on two of saidprojections, as shown inFig. 9, but as the casing 10 is thereaftertilted the globule of mercury will pass out of contact with the wire onone of said projections, and while remaining in contact with the wire onthe second of said projections, there will be an interval during whichthe circuit is interrupted until the tilting of the casing 10 continuessufficiently to bring the globule 11 into bridging relation with thewire on the next of said projections;

Sometimes it is desirable to provide for only open and closed positionsof the valve, in which is therefore in its wide open position.

may engage a contact I" suitably mounted at ill on said base plate. Theleads ill and 2 from said contacts I08 and I09 respectively may beconnected to the leads 43 and 42 respectively of the heating coil 4ianalogously as in the construction of Fi 1.

The construction illustrated in Fig. 1 provides a modulating valve whichis continuously under the control of the thermostatically operatedvariable resistance. To explain the operation, assume that the room iscold. The thermostat will then have moved the variable resistance fromthe position shown in Fig. 1 in a clockwise direction until the globuleof mercury 11 is substantially at the right-hand end of the casing 10 asviewed in that figure, and therefore the resistance of both the windingsand 8i will be interposed in circuit with the heating coil 4|. In thisposition the magnitude of the resistance current through the heatingcoil 4|. The spring 64 is now holding the expansible and collapsiblechamber 44 contracted, with its tubular stop 60 against the shoulder GI,and the valve disk 34 Steam is therefore flowing through the valvehousing "and surrounding the expansible and collaps- 'ible vessel 51,and said vessel is filled with the vapor of the volatile fluid but thetension of said vapor is insufficient to overcome the tension of thespring 64. The heating chamber 49, and also preferably the communicatingpiping 5i, are now filled with the liquid of the volatile fluid.

- As the temperature in the room rises the thermostat 9| moves thetube10 of the variable resistance device in an anti-clockwise direction asviewed in Fig. 1, and therefore the globule of mercury travelsrelatively to the left, as viewed in said figure, under the influence ofgravity to diminish the amount of resistance in circuit with the heatingcoil 4i and therefore permit an increased flow of currentlthrough thelatter. Coil 4| therefore heats the heating chamber 40 and causes anexpansion of the volatile liquid therein, forcing some of it into theexpansible and collapsible vessel 51 where it is volatilized by the heatof the steam surrounding said chamber. As the temperature in the roomcontinues to rise and the variable resistance device 10 is moved fartherto the right as viewed in Fig. 1 the resistance in the heating .coilcircuit is cut down to such a point that the heat created by said coilcauses the vapor pressure in the vessel 51 to exceed the resistance ofthe spring 64, and the chamber 51 therefore begins to expand under theprinciples heretofore described, moving the valve plate 34 toward itsseat and cutting down on the flow of steam through the radiator. Thiswill continue until a condition of equilibrium is reached.

If the room falls in temperature below that desired by reason of thethrottling of the steam inlet, the variable resistance device is movedin the opposite direction, increasing the resistance and decreasing thecurrent flowing through the coil 4|.. The heating chamber 40 thereforecools, owing to the dissemination of heat to the surrounding atmosphere,and the resulting vapor pressure in the chamber 51 is decreased, wherebythe spring 64 correspondingly collapses the-vessel 51 and moves thevalve disk 34 to a more open position. In practice it has been foundthat the thermostat will so position the variable resistance device asto maintain such a vapor pressure in the vessel 51 that the valve diskpermits the proper flow of steam to maintain a uniform temperature overlong periods of time, while any change in the temperature of the room byreason o a change in exterior temperatures, the opening of doors orwindows, etc., will result in a prompt and smooth readjustment of theposition of the valve disk with respect to its seat so as to increase ordecrease the steam flow suitably for compensating for the change inatmospheric conditions, eliminating the wide fluctuation, and also thecharacteristics of hunting, characteristic of earlier devices.

If it is desired that the valve be operated step by step upon theoccurrences of incremental changes of condition, the variable resistanceof Fig. 9 may be employed, or if it is desired that the valve have onlytwo positions, 1. e. that it be either open or closed, a make and breakdevice as in Fig. 6 may be employed.

It will therefore be perceived that an electrothermalLv-operated motorelement has been provided which-ishighly sensitive and quicklyresponsive to temperature conditions at the heating coil because of thepromptness with which the small volume of liquid in the heating chambermay respond to changes of heat produced'by the coil, while the amount ofenergy required at the coil is materially reduced by utilizing the heatof the steam as a source of energy in aiding in the expansion of theexpansible vessel. It will also be perceived that a variable resistancedevice has been provided which aflfords a highly sensitive andcontinuous control of the heating coil while eliminating the variationsof operation and resistances to movement characteristic of the variousforms of rheostat heretofore employed. Hence a modulating radiator valvehas been provided which is accurately and sensitively responsive tosmall changes of temperature and which at the same time uses electriccurrent economically, although it is constantly under the control of thethermostat. As the heat energy required from the coil is only such as isnec to eil'ect the expansion of the liquid in the chamber I under theexisting pressure, the amount of current flowing through the coil issmall, and therefore the device is economical, while the electricalcontrolling mechanism employed may be compact and highly sensitivebecause of the fact that the current to be controlled is relativelyweak. This enables the maintenance of a continuous control of the valvefrom the electric circuit economically and thereby obtains the closeregulation and modulating efl'ect of a valve whose position is promptlyand accurately adjusted by small increments in response to slightvariations of temperature in the medium whose temperature is to becontrolled. At the same time, if desired, the improvedelectrothermally-operated motor device can be controlled by a make andbreak device in the electric circuit or in a step by step manner, orwith less eilicient rheostats, while still obtaining many of theadvantages of the present invention. It will also be apparent that theimproved variable resistance device can also be used with other forms ofelectrothermally-operated motor devices and also that it is capable-of awide variety of other usesi While the embodiments of the: inventionillustrated on the drawings have been described with considerableparticularity, it is to be expressly understood that the invention isnot restricted thereto, as the same is capable of receiving a variety ofexpressions within the principles heretofore disclosed, while changesmay be made in with said heating chamber, means to vary the curthedetails, arrangement, proportion and sizes of parts, and certainfeatures used without other features, without departing from the spiritof this invention. Reference is therefore to be had to the appendedclaims for a definition of the limits of the invention. I

What is claimed is:

1. In a modulating radiator valve, in combination with a valvemechanism, an electrothermallyoperated motor comprising an expansibleand collapsible vessel operatively connected to said valve mechanism andsubjected to the heat of the medium to be controlled, a heating chamberof small volume communicating with said vessel and charged with avolatile fluid whose boiling tem- 1 perature is below the temperature ofsaid heating medium, a heating coil associated with said heatingchamber, and means to vary the current flow through said heating coil.

2. In a modulating radiator valve, in combination with a valvemechanism, an electrothermally-operated motor comprising an expansibleand collapsible vessel operatively connected to said valve mechanism andsubjected to the heat of the medium to be controlled, a heating cham- 2ber of small volume communicating with said vessel and charged with avolatile fluid whose boiling temperature is below the temperature ofsaid heating medium, a heating coil associated with said heatingchamber, and the current flow through said heating coil, said last namedmeans including a variable resistance and thermostatic means foradjusting the magnitude of said resistance.

3. In a modulating radiator valve, in combi- 3 nation with a valvemechanism, an electrotherm'ally-operatedmotor comprising an expansibleand collapsible vessel operatively connected to said valve mechanism andsubjected to the heat of the medium to be controlled, a heating chamberof small volume communicating with said vessel and charged with avolatile fluid whose boiling temperature is below the temperature ofsaid heating medium, a heating coil associated rent flow through saidheating coil, said last named means including a .variable resistanceadapted to maintain constantly a current through said heating coil,.andmeans to progressively vary the magnitude of said current.

4. In a modulating radiator valve, in combination with a valvemechanism, an electrothermally-operated motor comprising an expansibleand collapsible vessel operatively connected to said valve mechanism andsubjected to the heat of the medium to be controlled,'a heating chamberof small volumecommunicating with said vessel and charged with 'avolatile fluid whose boiling temperature is below the temperature ofsaid heating medium, a heating coil associated 6 with said heatingchamber, means to vary the current flow through said heating coil, saidlast named means including a variable resistance adapted to maintainconstantly a flow of current through said heating coil, and a thermostatG operatively connected to said variable resistance to progressivelyvary the resistance of said device.

5. In a modulating radiator valve, in combination with a valvemechanism,an electrothermallyoperated motor comprising an expansible andcollapsible vessel operatively connected to said valve mechanism andsubjected to the heat of the medium to be controlled, a heating chamberof small volume communicating with said vessel and charged with avolatile fluid whose boiling tem- 7 means to vary 30 perature is belowthe temperature of said heating medium, a heating coil associated withsaid heating chamber, and thermostatic means for predetermining thecurrent flow through said heating coil.

6. In a modulating radiator valve, in combinationwlth a valve mechanism,an electrothermallyoperated motor for operating said valve mechanism andincluding an expansible and collapsible vessel operatively connected tosaid valve mechanism, means for subjecting said vessel to heat, aheating chamber of relatively small volume in communication with saidvessel and charged with a volatile fluid whose boiling temperature isbelow the temperature at said vessel, a heating coil associated withsaid heating chamber, and means for varying the current flow throughsaid coil.

7. In a modulating radiator valve, in combination with a valvemechanism, an electrothermallyoperated motor element for operating saidvalve mechanism and including an expansible and collapsible vesseloperatively connected to said valve mechanism, means for subjecting saidvessel to heat, a heating chamber of relatively small volume incommunication with said vessel and charged with a volatile fluid whoseboiling temperature is below the temperature at said vessel, said chargebeing of such volume that said heating chamber is full of said volatileliquid when said expansible and collapsible vessel is in its mostcontracted condition, a heating coil associated with said heatingchamber, and means for varying the current flow through said coil.

8. In an electrothermally-operated device, in combination with a memberto be operated, an expansible and collapsible vessel operativelyconnected to said member, a heating chamber in communication with saidvessel, a heating coil associated with said chamber, means forcontrolling the flow of current through said coil to heat said chamber,said heating chamber being of relatively small volume as compared withthe volume or said vessel and being charged with a volatile liquid, andmeans for heating said vessel to a temperature which will maintain onlyvapor in said vessel.

9,. In an electrothermally-operated device, in combination with a memberto be operated, an expansible and collapsible vessel operativelyconnected to said member, a heating chamber in communication with saidvessel, aheating coil associated with said chamber, means forcontrolling the flow of current through said coil to heat said chamber,said vessel and chamber being charged with a volatile fluid and saidchamber being of such small volume thatthe ratio ofthe maximum volume ofsaid vessel and chamber to the volume of said chamber is approximatelyequal to the ratio 01' the vapor volume to the liquid volume of a givenmass or said volatile fluid, and means for subjecting the said vessel toa temperature which will maintain only vapor in said vessel.

10. In an electrothermaliy-operated device, in combination with a memberto be operated, an expansible and collapsible vessel operativelyconnected to said member, a heating chamber in communication with saidvessel, a heating coil associated with said chamber, means forcontrolling the flow of current through said coil to heat said chamber,said vessel and chamber being charged with a volatile fluid which, whensaid chamber is relatively cool, completely fills the same and saidvessel having a volume which, when expanded, is substantially equal tothe increase in volume of said liquid when vaporized, and means forsubjecting said vessel to a temperature which will maintain only vaporin said vessel.

11. In an electrothermally-operated device, in 5 combination with amember to be operated, an expansible and collapsible vessel operativelyconnected to said member, a heating chamber in communication with saidvessel, a heating coil associated with said chamber, means forcontrolling the flow of current through said coil to heat said chamber,said chamber and vessel being charged with a volatile fluid, means forsubjecting said vessel to a temperature which will maintain only vaporin said vessel, and means for subjecting said vessel to resilientpressure, said chamber being of such small volume'that the volumetricchange from liquid to vapor of a'volume of liquid substantially equal tothe volume of said chamber under the existing pressuresis substantiallyequal to the change in volume of said vessel when expanded from its mostcontracted to its a most expanded condition. 7

12. In an electrothermally-operated device, in combination with a memberto be operated, an 25 expansible and collapsible vessel operativelyconnected to said member, a heating chamber in communication with saidvessel, a heating coil associated with said chamber, means forcontrolling the flow of current through said coil to 30 heat saidchamber, said chamber and vessel being charged with a volatile fluid,means for subjecting said vessel to a temperature that will maintainonly' vapor in said vessel, the volume of said chamber being so relatedto the volume of 35 said fluid that when saidchamber is relatively coolsaid chamber is substantially full of said liquid and said vesselcontains only vapor and when said vessel is in its most expandedcondition and said chamber is hot substantially the entire volume ofsaid fluid is vapor. I

13. In an electrothermally-operated device, in

combination with a member to be operated, an

expansible and collapsible vessel operatively connected to said member,a heating chamber in 45 communication with said vessel, a heating coilassociated with said chamber, means for con-. trolling the flow ofcurrent through said coil to heat said chamber, said chamber and vesselbeing charged with a volatile vapor, and means for subjecting saidvessel to a temperature Such that said vessel normally contains only thevapor of said fluid, said chamber being of relatively small volume ascompared with said vessel but providing sumcient of said volatile fluidthat when vaporized it will expand said vessel to its most expandedcondition.

14. A modulating valve comprising, in combination with valve mechanism,an expansible and collapsible vessel operatively connected to 50 saidvalve mechanism, a relatively small heating chamber in communicationwith said vessel and charged with a volatile fluid, means for subjectingsaid vessel to a heated medium whose normal temperature is above theboiling point of said fluid, saidchamber being or such small volume thatthe ratio of the maximum volume of said vessel and chamber to the volumeof said chamber is approximately equal to the ratio of the vapor volumeto theliquid volume of a given mass 01 v collapsible vessel operativelyconnected to said valve mechanism, a relatively small heating chamber incommunication with said vessel and charged with a volatile fluid, meansfor subjecting said vessel to a heated medium whose normal temperatureis above the boiling point oi. said fluid, the volume of said chamberbeing so related to the volume of said fluid that when said chamber isrelatively cool said chamber is substantially full of said liquid andsaid vessel contains only vapor and when said vessel is in its mostexpanded condition and said chamber is hot substantially the entirevolume of said fluid is vapor, a heating coil associated with saidchamber, and

means for intermittently making and breaking the circuit through saidheating coil.

16. A modulating valve comprising, in combination with valve mechanism,an expansible and collapsible vesssel operatively connected to saidvalve mechanism, a relatively small heating chamber in communicationwith said vessel and charged with a volatile fluid, means for subjectingsaid vesel to a heated medium whose normal temperature is above theboiling point of said fluid, a heating coil associated with saidchamber, and means for progressively varying the cir cuit through saidheating coil.

17. A modulating valve comprising, in combination with valve mechanism,an expansible and collapsible vessel operatively connected to said valvemechanism, a relatively small heating chamber in communication with saidvessel and charged with a volatile fluid, means for subjecting saidvessel to a heated medium whose normal temperature is above the boilingpoint of said fluid, a heating coil associated with said chamher, andmeans for controlling the current :flowing through said heatingcoilincluding a thermostatically operated variable resistance.

18. A modulating valve comprising, in combination with valve mechanism,an expansible and collapsible vessel operatively connected to said valvemechanism, a heating chamber in communication with said vessel andcharged with a volatile fluid, means for subjecting said vessel "to aheated medium whose normal temperature is above the boiling point ofsaid fluid, a heating coil associated with said chamber, and athermostatically operated device for predetermining the operation ofsaid heating coil.

19. A modulating valve for controlling a heated medium comprising, incombination with valve mechanism, an expansible and collapsible vesseloperatively connected to said valve mechanism and subjected to the heat01' said medium to be controlled, a relatively small heating chamber incommunication with said vessel and charged with a volatile fluid whoseboiling temperature is below the temperature of said heated medium, aheating coil associated with said heating chamber, and means to vary theflow of current through said heating coil.

20. A modulating valve for controlling a heated medium comprising, incombination with valve mechanism, an expansible and collapsible vesseloperatively connected to said valve mechanism and subjected to the heatof said medium to be controlled, a relatively small heating chamber incommunication with said vessel and charged with a volatile fluid whoseboiling temperature is below the temperature of said heated medium, aheating coil associated with said heating chamber, and thermostaticallycontrolled means for progressively varying the flow of current throughsaid heating coil.

21; An electrically controlled modulating radiator valve comprising, incombination with valve mechanism, an expansibl'e and collapsible vesseloperatively connected with said valve mechanism and subjected to theheated medium to be controlled, a heating chamber in communication withsaid vessel, said chamber being charged with a volatile fluid whoseboiling point is below the temperature of said heated medium, a heatingcoil associated with said heating chamber, and means to predetermine theheating effect of said coil, said chamber being relatively small andcontaining substantially only so much of said volatile liquid as isrequired to provide the vapor requisite to expand said vessel under theheat of said heated medium when said coil is heated to the requisitedegree.

JEAN v. GIESLER. WILLIAM B. MACKINTOSI-I.

